A unique real estate partnership including the University of California’s QB3 institute will expand San Francisco’s amount of biotech incubator space by 50 percent, providing enough room for 20 to 30 young companies.

QB3 and Dewey Land Co. Inc. expect to open a new life sciences incubator — about 24,000 square feet at 953 Indiana St. in the city’s Dogpatch neighborhood — in September. It would be the sixth space for biotech startups in the city and the fifth in the Bay Area network of QB3, or the California Institute for Quantitative Biosciences.